Method and apparatus for ironing leather

ABSTRACT

A throughfeed ironing machine and the method of ironing leather sheets therein. The ironing apparatus includes a heated ironing plate disposed on one side of a pass line extending through the machine, along which an ironed leather sheet travels. An oscillatable pressure plate is disposed opposite the ironing plate on the other side of the pass line, and an endless belt is disposed between said plates and aligned with the pass line in the plate area to transport the leather to be ironed through said machine. In the practice of the method, leather sheets are fed through the machine between the plates, being heated and cyclically pressed therebetween, and advanced during the intervals of pressure rise and falls between the plates. In the method, the pressure plate is oscillated at a frequency of from 5 to 50 cycles per second, with the ironed leather being advanced on the rise and fall thereof, thereby giving the quality of a hand ironed finish to the leather.

[4 1 Apr. 17, 1973 [54] METHOD AND APPARATUS FOR IRONING LEATHER [75] Inventor: Jirl Dokoupil, 637 Oberursel/Taunus, Germany [73] Assignee: USM Corporation, Boston, Mass.

[22] Filed: June 14, 1971 211 Appl. No.: 152,663

30 Foreign Application Data June 15, 1970 Germany ..P 20 29 405.7

[52] US. Cl ..69/48, 38/10 51 int. Cl. ..c 14b 1/30 [58] Field of Search ..69/47, 48, 21; 38/7-11; 100/93 P, 154, 151

[56] References Cited UNITED STATES PATENTS 1,744,086 l/l930 Troisi ..38/10 X 1,153,289 9/1915 C1ements.... ..38/10 2,298,113 10/1942 Ely ..38/93 3,480,461 11/1969 Lynge ..38/97 X 2,392,695 l/l946 Rohdin ..lOO/93 P 3,185,614 5/1965 Van Hartesveldt et al ..100/93 P 2,271,656 2/ 1942 McLaughlin ..69/48 3,107,447 10/1963 Tucci ..38/10 FOREIGN PATENTS OR APPLICATIONS 986,006 3/1965 Great Britain ..69/48 Primary ExaminerAlfred R. Guest Attorney-Richard A. Wise et a1.

[57] ABSTRACT A throughfeed ironing machine and the method of ironing leather sheets therein. The ironing apparatus includes a heated ironing plate disposed on one side of a pass line extending through the machine, along which an ironed leather sheet travels. An oscillatable pressure plate is disposed opposite the ironing plate on the other side of the pass line, and an endless belt is disposed between said plates and aligned with the pass line in the plate area to transport the leather to be ironed through said machine. In the practice of the method, leather sheets are fed through the machine between the plates, being heated and cyclically pressed therebetween, and advanced during the intervals of pressure rise and falls between the plates. ln the method, the pressure plate is oscillated at a frequency of from 5 to 50 cycles per second, with the ironed leather being advanced on the rise and fall thereof, thereby giving the quality of a hand ironed finish to the leather.

. 10 Claims, 4 Drawing Figures METHOD AND APPARATUS FOR IRONING LEATHER BACKGROUND OF THE INVENTION In the ironing of leather, the surface of a sheet is subjected to heat, under pressure of an ironing tool, for a predetermined period of time. Conventional methods and apparatus may include a conveyor to transport the sheet to be ironed, a heating plate and a cooperating pressing or ironing plate. The conveyor-type apparatus is usually set to operate in a progressive stepwise manner, with the piece of leather to be ironed brought between the then extended cooperating plates.

While the leather is between the plates, they are activated (i.e., heated and pressed together) and then released and the conveyor is stepped forward, carrying the ironed piece of leather from between the plates.

The cycling of the conveyor and plates of the conventional apparatus requires several seconds for each operation which includes time for heating and subsequent pressing of the leather. For large pieces, several cycles may be required to complete ironing. Thus, it may be seen that severe limitations exist on the output capacities of the apparatus.

In an attempt to overcome the cyclical character of present machines, continuous ironing machines have been produced which may include two large rotary drums. In this type of apparatus, the leather is passed between the drums and pressed therebetween. One of the rolls may be heated to enhance the process. An inherent problem with this type of apparatus, however, has been the non-uniformity of product exiting the machine. It has been found that the piece of leather being ironed may be either telescoped into itself (foreshortened) and/or overstretched, on one or both surfaces.

Both of the above types of ironing method and apparatus suffer from the disadvantage that no relative motion occurs between the heated plate and the piece of leather during the ironing process. Those familiar with the art will recognize that a special surface quality in the ironed piece is brought about or enhanced by the gliding of a heated tool (iron) AGAINST the piece, as during manual ironing, with a heated hand iron.

SUMMARY OF THE INVENTION The problem solved by this invention is the requirement in the leather finishing industry for a method and apparatus providing a continual subjection of leather to heat and pressure, at a high rate of speed which at least duplicates the surface quality produced by hand/manual ironing.

To this end and in accordance with certain features of the invention, a piece of leather to be ironed is pressed between plates, at least one of which is heated, the pressure between the plates being fluctuated at a frequency of from to 50 cycles per second. The piece of leather being so ironed is advanced through the apparatus during the pressure fluctuations. Consistent with the method of ironing, the piece is subjected to I maximum pressures and heat only for short durations as the cyclical pressure peaks. The respective periods of rising and falling pressure are. utilized to move the leather along, i.e., in intimate surface contact with the heated plate.

The apparatus in which the method may be performed may include belt or conveyor means to transport the leather through the apparatus during ironing and at least one pair of pressure plates disposed on opposite sides of the pass line of the leather through the apparatus. Preferably, the pressure exerted by the plates may be controlled to a predetermined range and oscillated therein by means such as a mechanical eccentric or hydraulic equivalent. The transport means may include a rotary power source coupled through a slip clutch to the transport belt so that the leather may be advanced on the rise and fall of pressure exerted by the plates.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view, in section, of an ironing machine according to the invention;

FIG. 2 is a partial sectional view of an alternative embodiment of an oscillating pressure plate in the apparatus of FIG. 1;

FIG. 3 is an elevational view, in section, of an alternative embodiment of an ironing machine according to the invention; and I I FIG. 4 is an elevational view, in section, of another alternative embodiment of an ironing machine according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENT Referring now to the drawings in general and to FIG. lin particular, reference numeral 2 indicates generally a machine for ironing leather. A frame 4 has mounted therein a pressure plate 6, which may be heated and cooled by means 17 known but not shown in the embodiment illustrated. Plate 6 has a flat, smooth ironing I surface 8 and is mounted on height adjusting means 10, such as a hydraulic cylinder means, well known in the art. In the preferred embodiment, means 10 is adjustable to set surface 8 of plate 6 to a preselected height. Disposed opposite plate 6 is a second pressure plate 12 preferably having a surface 14 thereon of an elastic or resilient material such as rubber or felt. Plate 12 is mounted on means 16 for oscillating plate 12 in accordance with the method subsequently described. Oscillating means 16 may include mechanical eccentric means known in the art, or a variable pressure hydraulic expander 18, for example, as shown in FIG. 1. Hydraulic expander 18 may include a resilient membrane 20 over which support member 22 is disposed. Restraining springs 24 may be disposed between support member 22 and frame 4 to return plate 12 to its original position upon relaxation of expander 18.

Referring again to FIG. 1, an endless belt 26 or other suitable transport means is disposed between plates 6 and 12. Belt 26 may be supported by means such as rollers 28 capable of moving belt 26 through the ironing machine 2. A rotary power source such as an electric motor (not shown) may be coupled to a drive roll 30 through a slip clutch 32.

As an additional feature, a second driving roll 34 may be disposed above roll 30. Roll 34 is preferably positioned to intercept a sheet L of leather transiting the machine 2 and assist its advance through the machine. Further to facilitate the advance of sheet L, plate 6 may be coated with a material having a very low coefficient of friction, such as polytetrafluoroethylene, one type of which is available under the tradename Teflon.

Referring now to FIG. 3, a preferred embodiment of the ironing machine 2 of FIG. 1 is illustrated. As in the previous embodiment, a frame 4' includes a pressure plate v6 having a flat smooth ironing surface 8 and disposed on height adjusting means 10. Opposite plate -6' is a second pressure plate 12' also preferably having a resilient surface 14' thereon. Plate 12' is disposed upon oscillating means 16' capable of reciprocating plate 12 vertically with the frequency range of 5 to 50 cycles per second as in the earlier embodiment. A belt 26' disposed on rollers 28' is advanced by a drive roll 7 30- which is connected through a slip clutch 32' to a rotary power source (not shown).

The preferred embodiment of FIG. 3 also includes a third pressure plate 40 disposed adjacent plate 12', but on the entry side of machine 2', and cooperable with plate 6' to fonn a pre-ironing zone 42. Plate 40 is supported on a base 41 on height adjusting means 44 such as a hydraulic cylinder 46 and piston 48 activated by means not shown but well known in the art. Slidable guiderods 50 located in bores 52 may be included in means 44 to prevent tilting of plate40 in base 41. Likewise, the preferred embodiment includes a fourth pressure plate 54 disposed adjacent plate 12, but on the exit side of machine 2, plate 54 being also cooperable with plate 6' to form a post-ironing zone 56. Plate 54 is supported in a base 58 on height adjusting means 60 such as a hydraulic cylinder 62 and piston 64. Slidable guide rods 66 located in bores 68 may be included in meansi60 to prevent tilting of plate 54 in base 58.

In'the embodiment of the ironing machine 2' illustrated in FIG. 3, plate 6'-extends transversely through machine 2' so as to cooperate with all of plates 12, 40 and 54. Further,- plate 6' is provided with'a working surface 8 of a smooth material, being both heat conductive and of a low coefficient of friction. In the illustrated embodiment a foil such as polished, stainless steel is utilized, being storedupon a supply reel 70 and.

polished stainless steel, is supported upon rollers 76,

78, 80 and 82. Preferably, at least one of the rollers 78 82 will be controllable and driven. It is advantageous to cause belt 74 to travel through machine 2" at a slower rate than belt 26" to provide frictional ironing action on the leather. To accomplish the difference of rate, roll 82 may be coupled to the rotary power source (not shown) of roll 30" but geared down to a slower speed.

In operation of the embodiment of FIG. 1, driving roll 30 is engaged through slip clutch 32 to the rotary power source (not shown). As roll 30 rotates, belt 26 travels through machine 2 around the periphery established by rolls 28. .A sheet of leather L is laid on belt 26 and carried into the machine 2 to be ironed by the interaction of plates 6 and 12.

In operation of the machines of FIGS. 1, 3 and 4, oscillating means 16 is activated to reciprocate plate 12 toward and away from plate 6. The frequency of oscillation ismaintained substantially constant between 5 and 50 cycles per second. In the preferred practice of ironing disclosed the frequency of pressure applications of plate 12 is about 10 cycles per second. At this frequency of pressing, the belt 26 is driven past plates 6 and 12 at a speed of approximately 10 inches per second. During ironing, the temperature of the heated ironing plate 6 may be operated around 400F-as a convenient temperature. The ironing pressure between the oscillating plate 12 and heated plate 6 may oscillate in a range from a few pounds to 250 pounds per square inch. It should be realized by those familiar with the art that the above temperatures, rat'es'and pressures are illustrative only and must be adjusted to the particular type, thickness moisture content, and grade of leather. being ironed. Expectedly, a thinner piece of leather In the preferred embodiment of machine illustrated in FIG. 3, it has been found that lower specific pres-.

sures between plates 6' and 12' may be utilized by pre and post ironing via plates 6' and 40 and 54 respectively. It has also been found that such a combinationmay be used to thus materially increase the output .of the ironing machines of my invention. In ironing a piece of leather in this machine, a less pressure is usually exerted between plates 6' and 40 and 6' and 54 than the peak between plates 6" and '12. In zones 42 and 56 the sheet of leather L may be straightened and flattened, and undesirable wrinkles removed. In zone 42, the sheet L will be preheated so that lesser specific temperatures and pressures will be required at plates 6' and 12'. The pre and post ironing zones 42 and 56 also permit the machine 2 to be operated at a faster output rate than a machine 2 of FIG. 1 not having such capabilities.

As previously described, the ironing surface 3' of FIG. 3 is readily changeable should it become roughened or otherwise deteriorated. The heat c'onductive foil may be conveniently advanced by paying out off roll and taken up on roll 72. This may be done manually, or, if desired, may be mechanized or automated. I

In the apparatus illustrated in FIG. 4, a higher throughfeed rate of leather sheets L may be maintained. This machine 2" is operated similarly to those previously described. In this machine, however, belt 74 may provide a substantially continuing relative motion or ironing surface 8f along plate 6" byindividually driven belt 74. Thus, the effect of hand ironing continues during the pressure application by virtue of the continuing motion of belt 74 relative to sheet L on belt 26". As with the apparatus of FIG. 3, machine 2" provides quality ironing at increased output rates at temperatures and pressures below those of FIG. 1.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for ironing a sheet of material, such as leather, between plates by subjecting it to the action of heat, pressure and motion relative to said plates comprising: a frame, means for transporting said sheet through said frame along a pass line, a first ironing plate mounted on said frame having a smooth ironing surface thereon disposed adjacent said pass line, a

second ironing plate mounted on said frame having a smooth surface thereon disposed adjacent said pass line, opposite to and cooperable with said first plate, means for supplying heat to at least one of said plates, means to force said plates together for applying an ironing pressure between said plates, said forcing means supplying a substantially continuing ironing pressure to said sheet by the action of said plates, means for fluctuating said force applied by said last named means within a predetermined range thereby causing said continuing ironing pressure to fluctuate, and means for advancing said transporting means and said workpiece between said plates during the continuing of rise and fall of said fluctuating ironing pressure.

2. Apparatus according to claim 1 wherein said means to apply an ironing pressure includes said first plate fixed on means to adjust said plate normally relative to said pass line.

3. Apparatus according to claim 2 wherein said means for transporting said workpiece through said frame includes at least two transport rollers mounted on said frame and an endless belt disposed on said rollers such that a portion of said belt travels along said pass line between said plates and wherein said means for advancing said workpiece includes a rotary power source driving at least one of said rollers through slip clutch means whereby said belts travel may be interrupted by the ironing pressure between said plates reaching a predetermined level.

4. Apparatus according to claim 3 wherein said means for fluctuating said ironing pressure includes one of said plates coupled to eccentric means such that the reciprocating motion produced therefrom is substantially normal to said pass line.

5. Apparatus according to claim 3 wherein said means for fluctuating said ironing pressure includes fluid pressure cylinder motor means coupled to one of said plates, and fluctuating pressure hydraulic supply means, said motor means disposed to reciprocate said plate normally relatively to said pass line.

6. Apparatus according to claim 3 wherein said heated plate is adapted with a surface of high heat conductivity and low coefficient of friction.

7. Apparatus according to claim 6 wherein said fluctuated plate is adapted with a resilient surface.

8. Apparatus according to claim 3 including at least one additional ironing plate disposed adjacent said second plate along said pass line, adapted to cooperate with said first plate whereby an additional ironing zone is added to said apparatus.

9. A method of ironing a sheet workpiece such as a leather hide between ironing plates by the action of heat, pressure and relative motion of said plates com prising the steps of: passing said workpiece between two ironin plates, heating said workpiece b heating at least one 0 said plates, sub ecting said wor piece to a fluctuating ironing pressure by reciprocating said plates relatively heightwise of each other, and advancing said workpiece between said plates during the periods of fluctuating pressure rise and fall.

10. The method according to claim 9 wherein said fluctuating ironing pressure is oscillated at a frequency of from 5 to 50 cycles per second. 

1. Apparatus for ironing a sheet of material, such as leather, between plates by subjecting it to the action of heat, pressure and motion relative to said plates comprising: a frame, means for transporting said sheet through said frame along a pass line, a first ironing plate mounted on said frame having a smooth ironing surface thereon disposed adjacent said pass line, a second ironing plate mounted on said frame having a smooth surface thereon disposed adjacent said pass line, opposite to and cooperable with said first plate, means for supplying heat to at least one of said plates, means to force said plates together for applying an ironing pressure between said plates, said forcing means supplying a substantially continuing ironing pressure to said sheet by the action of said plates, means for fluctuating said force applied by said last named means within a predetermined range thereby causing said continuing irOning pressure to fluctuate, and means for advancing said transporting means and said workpiece between said plates during the continuing of rise and fall of said fluctuating ironing pressure.
 2. Apparatus according to claim 1 wherein said means to apply an ironing pressure includes said first plate fixed on means to adjust said plate normally relative to said pass line.
 3. Apparatus according to claim 2 wherein said means for transporting said workpiece through said frame includes at least two transport rollers mounted on said frame and an endless belt disposed on said rollers such that a portion of said belt travels along said pass line between said plates and wherein said means for advancing said workpiece includes a rotary power source driving at least one of said rollers through slip clutch means whereby said belt''s travel may be interrupted by the ironing pressure between said plates reaching a predetermined level.
 4. Apparatus according to claim 3 wherein said means for fluctuating said ironing pressure includes one of said plates coupled to eccentric means such that the reciprocating motion produced therefrom is substantially normal to said pass line.
 5. Apparatus according to claim 3 wherein said means for fluctuating said ironing pressure includes fluid pressure cylinder motor means coupled to one of said plates, and fluctuating pressure hydraulic supply means, said motor means disposed to reciprocate said plate normally relatively to said pass line.
 6. Apparatus according to claim 3 wherein said heated plate is adapted with a surface of high heat conductivity and low coefficient of friction.
 7. Apparatus according to claim 6 wherein said fluctuated plate is adapted with a resilient surface.
 8. Apparatus according to claim 3 including at least one additional ironing plate disposed adjacent said second plate along said pass line, adapted to cooperate with said first plate whereby an additional ironing zone is added to said apparatus.
 9. A method of ironing a sheet workpiece such as a leather hide between ironing plates by the action of heat, pressure and relative motion of said plates comprising the steps of: passing said workpiece between two ironing plates, heating said workpiece by heating at least one of said plates, subjecting said workpiece to a fluctuating ironing pressure by reciprocating said plates relatively heightwise of each other, and advancing said workpiece between said plates during the periods of fluctuating pressure rise and fall.
 10. The method according to claim 9 wherein said fluctuating ironing pressure is oscillated at a frequency of from 5 to 50 cycles per second. 